Technical Field
The present invention relates to an image forming apparatus, an image forming system, and an image processing method.
Description of Related Arts
With an image forming apparatus for forming an image, when images are formed on sheets on the basis of image data in units of pages, the image data in units of pages are stacked in a page memory, and various kinds of image processing is applied to the stacked image data in accordance with a processing speed of a printer, and then the processed image data is transmitted to the printer. At this occasion, it is necessary to maintain consistency of the processing speed between the transfer of the image data to the page memory and the reading process from the page memory.
In the technique disclosed in Patent Literature 1 (Japanese Patent No. 4895148), in a configuration in which multiple scanners and multiple printers are connectable to a controller in any given combination, the controller is provided with a page memory in order to absorb the difference of the process speed between them both when the printer prints image data of an original document read by the scanner. Then, in a case where the process speed of the connected printer is higher than the process speed of the scanner, the controller performs the following delay control so as not to exhaust the image data in the page memory before finishing the writing of the image data for a single original document sheet. When the image data is started to be transmitted to the printer from the page memory before finish of writing to the page memory of the image data read by the scanner, the controller determines timing for starting transmission of the image data from the page memory to the printer on the basis of the difference of the process speed between the scanner and the printer and the size of the image data.
As another technique, the image forming apparatuses include an apparatus that supports not only a cut sheet such as an A4 size but also a continuous sheet such as a roll sheet. The continuous sheet has, for example, a width of several dozen millimeters and a length of several hundred meters or several kilometers in the conveying direction.
Since the continuous sheet has a large sheet surface, multiple page images can be printed while the page images are continuously arranged in the conveying direction. At this occasion, a margin area which is an area between page images, i.e., a space between images, is a useless area, and it is necessary to, e.g., discard the margin area after it is cut in the post processing performed after the printing. Therefore, the image interval is preferably made to be as narrow as possible.
It is necessary to execute image processing on each of the page images with hardware supporting applied functions such as stamps and characteristics of the image forming unit. The parameter of the image processing is set to a different value for each page image. Therefore, it is necessary to perform the setting processing at a time between images where a page is switched. In a case where a cut sheet is used, it is necessary to make a space between sheets in order to convey each of the sheets, and in general, the sheet interval is about 30 to 50 mm. In this case, the processing of the parameter setting for a subsequent page image performed between pages can be processed within a period of time allocated in the sheet interval (image interval). On the other hand, in a case where a continuous sheet is used, it is not preferable to provide an image interval of 30 to 50 mm from the view point of reduction of the margin area, and it is preferable to set an image interval of about several millimeters to about 1 mm.
However, when the image interval is set to about 1 mm, the processing of the parameter setting performed between images for each page image cannot be done in time, and this processing becomes a bottleneck, which makes it impossible to sufficiently reduce the image interval. In the technique disclosed in Patent literature 1, the timing for starting transmission from the page memory to the printer is adjusted, and this can prevent the image data from being exhausted during transmission from the page memory to the printer, but the technique disclosed in Patent literature 1 cannot solve the problem to more greatly reduce the image interval.
The present invention is made in view of the above circumstances, and it is an object of the present invention to provide an image forming apparatus that can ensure a processing time for parameter setting performed between images even when an image interval is set to be shorter, e.g., even when a continuous sheet is used, and therefore, the image forming apparatus can appropriately perform image processing on image data in units of pages.